Study identifies previously unknown role of microglia in neurodevelopment.

The brain consists of two major types of cells, namely neurons and glial cells, with the immune-based glial cells providing support and protection for neurons in the central and peripheral nervous systems.  While neurons have been studied for more than a century, extensive glial research has only developed recently.  Now, a study from researchers at New York University shows glia are vital to nerve-cell development in the brain.  The team states this previously unknown source for the brain’s development offers new insights into the origins of the nervous system.  The study is published in the journal Science.

Previous studies show glia are not the mild-mannered understudies they appear to be, with some microglia known to fire electrical signals. For the past few years, it has become evident the functioning of the brain can only be understood if the interaction of all cell types, namely neurons and glial cells, is understood.  The current study identifies a role for glia in coordinating neuronal development across distinct brain regions.

The current study utilizes the Drosophila fly visual system to show how development is coordinated to establish retinotopy, a feature of all visual systems. Results show the coordination of nerve-cell development is achieved through a population of glia, which relays cues from the retina to the CNS to make cells in the brain become nerve cells.  Data findings show by acting as a signaling intermediary, glia have precise control over when and where each neuron is born, and the type of neuron it will develop into.

The lab explains photoreceptors achieve retinotopy by inducing their target field in the optic lobe which contains lamina neurons, using epidermal growth factor (EGF) as a  secreted differentiation cue.  They go on to add in response to this photoreceptor-EGF glia produce insulin-like peptides, inducing lamina neuronal differentiation.

The team surmises their study implicates microglia in the timing, identity, and coordination of neurogenesis.  For the future, the researchers state their results may lead to a revision of the neuron-centric view of brain development.

Source: New York University (NYU)

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